Depending on the Tv mount but it boils down to the clearance from the wall itself. generally easier just to wall mount it behind the TV and that will keep it a little cooler than attached directly to the tv.

I use a low power atom based NAS to house my media I have used used a @30 watt atom as a core and does quite well so for about 60watts I have my fully functional core and my media available. Attaching usb sound cards to the NAS and having auto sensing power on amps gives me my audio only zones with little or no additional power draw. (Until amps are in use).Network based tuners solve many issues as well including power consumption.media storage does not require high cpu usage.media playing with accelerated drivers does not require high cpu usage.IP camera's with with dedicated motion sensors does not require high cpu usage

so unless you must use motion or must use hulu cpu requirements are quite slim

If you don't have one you may want to purchase a killowatt meter. You will be surprised by how much power is being drawn by common household items. Found ( Cable box was using 45w on or off)

1. Drop the bluray drive..... no support for that.2. Cheap cases generally come with cheap (inefficient)power supplies. Use 80plus certified.3. Cheap cases generally have loud fans.3. Atoms/ IONS are great for media only.4. The least expensive up front may not be in the end. Especially when you add in the time and frustration factor.5. Consider some ready to go MD's that address all the above.

The core can run on a low powered cpu or in a VM environment.The MD's actually do the heavy lifting. Accelerated video can off load a good portion of thatBut running MD desktop apps /hulu mame etc require a great deal of cpu